An experimental and numerical study for two phase flow (water-air) in rectangular ducts with compound turbulators

摘要

The improvement of heat transfer by using multiphase flow is a key focus in the energy industry and related applications such as steam turbines (power plants), steam generators and condensers, refrigeration, food manufacturing, and heating and cooling systems. Dispersed bubble two-phase flow (water-air) with heat transfer in a rectangular turbulated vertical canal with dimension 5 × 3 × 70 cm was thus studied in the current work and experimental and numerical studies were performed to test the influence of the superficial inlet velocity of air and water and the position of grooves at constant heat on the heat transfer coefficient and the temperature distribution along the test section. Water superficial inlet velocities were (0.0987, 0.1974, 0.296, and 0.395 m/s), while air superficial inlet velocities were (1.4609, 2.923, and 4.384 m/s), and the heat power was a constant (109.65 W). The results indicated that the local coefficients of the heat transfer for the experimental and numerical study were raised as the superficial inlet velocity rose. The opposite effect was indicated in terms of the temperature distribution along the test section which dropped as superficial inlet velocities rose. The presence of compound turbulation led to an enhancement of the experimental and numerical heat transfer coefficients over those seen in the smooth channel by (56.5% and 54.7%), respectively, for g/p = 0.55 and water and air superficial velocities of (0.395 m/s and 4.384 m/s). Good agreement was found between the experimental and numerical data, with the percentage deviation between the experimental and numerical results being only (5.77%).